Seam structure for flexible ventilating tubing



May 30, 1944. w. H. EVANS SEAM S'VI'RUCTURE FOR FLEXIBLE VENTILA'IVING TUBING l Filed Jan. 1o; 1941 I INVENTOR 'WILLIAM gjm y 5. N mn Em am EMA w..

Patented May 30, 1944` SEAM STRUCTURE FOR FLEXIBLE VENTILATING TUBING William HooperEvans, St. Louis, Mo.

, Application January 10, 1941, Serial No. 373,906

1 Claim.

The present invention relates to seam structure for flexible Ventilating tubing such as is used in mines, tunnels, and the like, for-carrying air into the tunnel headings, and various parts of mines, and has Yfor an object to provide a tubing preferably formed of heavy Wovenfabric having a `sawed seam which is effectually sealed against leakage under pressure and forrelatively long distances, so that it can be used with all typesof blowers, and particularly where it is preferable to use only one positive type of high pressure blower.

, Where flexible tubingis` used for delivering air at short` distances and in connection with centrifugalor-low pressure fans, lleakage at the seam does not seriously impair the function of the tube. Ithas been impractical, however, with the type of sewed` seam heretofore in use, to employ vsuch tubing Vfor long distances, say 3000 feet or more, Where comparatively high `pressures are used, and in cases where the run of tubing is as much as 5000 feetthe leakage has been found to be extremely high. Obviously such `performance overworks the fan anddoes not conduct a satisfactory amount of air .to the delivering point.

.y Leakage `at the seam `is commonly due to sewinggas this is done with heavy strong thread, requiring/ a large diameter needle, and 'as this needle punches holes larger than the thread, the lattery does not fill up the holes, with the result that there is a line of holes in the seam which permits air leakage, even under low pressures, and at relatively `high pressures the leakage over any considerable distance is so great that the tubing becomesimpractical. While lattempts have been made toproduce a leak-proof non-sewed seam by cementingand also by coating the outside of the seam ofythetubing with asphalt or similar material, these have not been satisfactory, as the methods have been costly and slow in production,` usually requiring hand-application and hand-rolling. The substances used would also soften under high temperatures, producing a sticky, smeary surface which would come off on the hands when the tubing was handled.

It is an object of the present invention to produce a sewed seam in which the needle holes will be effectually sealed, and to this end I particularly propose to incorporate in a sewed seam a strip of pliable resilient material such as rubber treated or coated cloth, which is combined in the seam in such manner that it closes about the threads of the seam in tightly sealed relation and provides a plug seal for the ends of the needle produced holes inthe adjacent layers of the tub.- ing` material, so that` while these holes in the tubing material do not themselves close in sealed relation around the threads the elastic strip yof material which is capable of closing tightly about the threads `does in effect close or `plug the holes in the tubing material at the points where leakage may occur. The elastic strip interposed in the seam is also `so arranged that during Ythe stitching operation the seam may Vbe compressed against the yieldability of the strip, so that `an extremely tight stitching will result,land the layf ers of the tubing material and the strip will thus be held in tight surface conforming relation contiguous to the stitching.

With the above and other objects in View, ern` bodiments of the invention are `shown in the accompanying drawing, and these embodiments will be hereinafter more fully described with reference thereto, and the invention will be finally pointed out inthe claim.

In the drawing:

Fig. 1 is a perspective View of a portion of flexible Ventilating tubing, according to my invention.

Fig. 2 is an enlargedside elevation of a portion of a short length of lthe seam portion of the tub-` ing.

Fig. 3 is a sectional view taken along the line 3--3 of Fig. 2. I

Fig. 4 is a sectional view of a modifiedform vof the invention.

Fig. 5 is a sectional View of a modied form of the invention, wherein the rope as shown in Fig. 3, is dispensed with.

Fig. 6 is a sectional view of another modification of the invention, wherein the rope as shown in Fig. 4, is dispensed with.

Similar reference characters indicate corresponding parts throughout the several gures of the drawing.

Referring to the drawing and particularly lto Figs. 1 to 3 thereof, thetubing material `I 0, which is preferably a heavyfwoven fabric as duck, drill,

` canvas, or the like, preferably treated, impreg- Another inverted U-shaped strip I4, preferably made from the same woven fabric as the tubing, is engaged over the sealing strip and encloses a rope member I5 which provides a longitudinal rib or enlargement adapted to have suspension clamps secured about it at suitable intervals in the usual manner. The seaml is secured by two rows of machine stitching I6 and II extending through thesix parallel layers produced by the several parts of the seam;

The material of the Ventilating tubing as above pointed out is a heavy Woven fabric, and is treated with substances which render it relatively Stiff, and from its nature the punch holes formed therein by the sewing needles do not contract after they are once made by the needle, and as these needles are very heavy and of larger diameter than the thread these holes cause space-s to remain about the threads at the points where they pass through the layers of the material. The sealing strip material is such, however, that the needle holes close tightly about the thread, as at I 8, after the needle is withdrawn. Also the compressive action of the stitching operation compresses the sealing layers so that they exert outward pressure on thevseam structure to hold the stitches tight and compress the layers into tight conforming relation to each other. Consequently the ends of the needle holes I9 in the tubing material are effectually plugged by the elastic material which tends to flow into these hole ends under the expansive action of the compressed sealing layers.

VWhile I have referred to the sealing strip material as a rubber coated fabric, it will be understood that any suitable material may be employed for this purpose, as long as it has the necessary pliability and resilience, has the characteristic that it will permit a hole to be punched therein, such as a needle hole, and will then close in tightly sealed relation around a thread engaged through the hole, and is of such nature that it may be cut into strip form and handled withafacility while in a relatively dry state. While rubber in various states and other materia'ls may be employed, a satisfactory material for the purpose is pure gum rubber, preferably uncured, and used as an all-rubber strip or as a coating over a fabric base. This may be of a self-curing type which will cure up after incorporation in the seam, this type having a longer life than the uncured type.

-v In Fig. 4 I have shown a modication in which the inverted U-shape sealing strip I3 is engaged over one longitudinal marginal edge portion II of the Ventilating tubing, While therother marginal edge portion I2 is engaged with one side of the sealing strip I3 and is provided with an integral extension 20 Which is carried over the reinforcing rope I5l and is then :carried downwardly into engagement with the other side of the sealing strip, the two rows o f stitching I6 and I'I 4being engaged through the several layers of the seam in a similar manner to the rst embodiment. vIn this arrangement the separate ment which encloses the sealing strip I3 at its outer sides to form a compressive member therefore is dispensed with, and the marginal portion I2 and its integral extension 20 are employed for the same purpose, so that when the layers are compressed through the stitching operation the sealing strip becomes compressed and thereupon exerts outward pressure to cause the stitching to become tight andthe several layers to be tightly pressed into conforming engagement with each other. Thus the elastic material of the sealing strip which closes about the stitching threads as at I8 constitutes a plug means for the covering strip Id employed in the first embodiends of the open spaces I9 of the needle punch holes in the tubing material, so that these holes areeffectually sealed against air leakage.

In Figs. 5 and 6 I have illustrated modifications in which the rope member I5 is dispensed with, these modifications corresponding otherwise to the embodiments of the invention illustrated in Figs. 3 and 4 respectively. In these modications grommets or other suitable suspension means may be incorporated in the seam.

I have illustrated and described preferred and satisfactory embodiments of the invention, but it will be obvious that changes may be made therein, within the spirit and scope thereof, as dened inthe appended claim.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

In a exible air-conducting Ventilating tubing wherein the tube is formed from a strip of rela`- tively thick substantially non-resilient woven fabric material incapable of substantial contraction toself-seal needle holes made therethrough having its longitudinal marginal edge portions brought together along a seam, a seam structure comprising an inner longitudinal two-layer n formed from said marginal edge portions of said tube, an inverted U-shaped sealing strip engaged about said fin formed from pliable resilient material capable of contraction to self-seal needle holes made therethrough, an inverted U-shaped covering strip engaged over said sealing strip and also formed from a Vstrip of thick substantially non-resilient wovenl fabric material incapable of substantial contraction to self-seal needle holes made therethrough, and needle-applied thread stitching extending through and securing the lay'- ers of said seam, the thread-applying needle being of greater thickness than the thickness of the thread,` lthe needle-produced holes through said ycovering strip and n being larger than the thread thickness through the incapacity of the material of the covering strip and iin to contract,

and the needle-produced holes throughsaid seal ing strip being tightly engaged by said thread'y through the capacity of the material of the sealingl strip to contract, and the relatively larger needle-produced holes in said covering strip and fin having their ends contiguous to said sealing strip plugged by the sealing strip material sur-- rounding the relatively smaller needle-produced holes in said sealing strip.

. WILLIAM HOOPER EVANS. 

